There is so much hype about blockchain technologies! Everyone is fascinated about it, dream about wonderful bright cryptofuture, and stops talking with me, when hears that I do not find blockchain either interesting or useful.
Why I do not like blockchains? Actually if they would work, from cryptographic point of view, then I have nothing against! Distributed trusted databases, timestamps and consensus making are great things to deal with. But unfortunately I see that at least Bitcoin (the biggest blockchain in use) has already failed without human-initiated regulations. It failed from cryptographic point of view.
I am cypherpunk and I am very interested and excited about cryptography subjects. Why? Because all of that is based on math and assumptions about practical impossibility of reverting many functions (you know, some kind of "2^100 of operations are required for ..."). It is valuable because you do not have to trust and rely on people at all. Well, except for cryptographers and similar scientists. People are the problem #1 in all security questions. They can be bribed, all of them have their price. They are error-prone, not reliable, lie and misbehave easily. I can not sleep soundly, knowing that I depend on some human. Cryptography world gives unbelievable possibility to eliminate them!
If I can easily remember relatively long passphrase (100-120 characters in practice) as a key to proven strong authenticated encryption algorithm, then I am confident that my data is safe. I can use eavesdropped links and virtually any potentially vulnerable storage when cryptography is applied correctly. While noone ever know if quantum computers powerful (big) enough will be built, RSA/ElGamal/ECC stay pretty safe too. I really love the fact of security risks estimation possibility, based on current technology state and progress. People can fail you anytime – only hope will keep you calm.
Are you afraid of algorithms breaking possibility? Even one of the first encryption algorithm used in computer era – DES, is still useful and secure enough in 3DES composition. If you are still frightened, then learn from soviets: their GOST 28147-89 block cipher, created in 1970s, still has more than 2^200 security margin. Who the hell knows what "key meshing" means? But that block cipher has that kind of thing, making it immune to Sweet32 attack, appeared dozens of years after. Do not overestimate value of performance, by sacrificing its security – perfect advice for sleeping well for years.
But what about blockchains? Citing Ethereum’s "problems" wiki page:
While a cryptographer is used to assumptions of the form "this algorithm is guaranteed to be unbreakable provided that these underlying math problems remain hard", the world of cryptoeconomics must contend with fuzzy empirical factors such as the difficulty of collusion attacks, the relative quantity of altruistic, profit-seeking and anti-altruistic parties, the level of concentration of different kinds of resources, and in some cases even sociocultural circumstances.
Everything is right here. Anyway you will depend on people, society, its behaviour and huge quantity of empirical factors and assumptions. It is not cypherpunk’s reliable and risks-predictable world – it has nothing in common. Replacing the need to trust the human, with the need to trust the algorithm and technology – that is the exact reason why I am interested in crypto. Requiring and depending on society again – that is the exact reason why I standing aside from blockchains. They do not offer any guarantees, but likelihoods, lottery.
Cypherpunk must rely and depend on people as little as he can. Remember cypherpunk’s manifesto – spread as little unnecessary information as possible, because people will find ways how to harm you with it. And blockchains are broadcasting permanent storages, where most of them (with Zcash exception for example) give you neither privacy nor anonymity for your personal (private) transactions.
Also there is good article: Blockchain is not only crappy technology but a bad vision for the future.